public class Main {
    public static void main(String[] args) {
        classStudent student1 = new classStudent();
        student1.id = 1234;
        student1.name = "zhangsan";
        student1.className = "Java2501";
        System.out.println(student1.toString());

        graduateStudent student2 = new graduateStudent();
        student2.years = "2025";
        System.out.println(student2.toString());

        newStudent student3 = new newStudent();
        student3.year = "2025";
        System.out.println(student3.toString());

        System.out.println("2025");
    }
}